Differential Thermal Research Articles

Differential thermal analysis techniques as a tool for preliminary examination of catalyst for combustion

The need for more economical catalysts for various combustion reactions is continuously driving catalyst development. We present Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) as suitable techniques for fast examination of catalyst activity for combustion reactions. The heat of reaction ΔHr generated at the catalyst in a combustible atmosphere is the measure for estimating the capability of the catalyst. Present investigations verify the reliability of both methods for the pre-selection of catalysts for further extensive investigations. To simplify the measurements and the result evaluation, a new measurement routine is introduced which is more suitable for rapid catalyst investigation than the conventional approach. For initial investigations, oxidation of 1% methane on a cobalt oxide catalyst was used. First, DTA measurements were performed. The vessel size and the amount of catalyst are considered as factors influencing the thermal signal. Simultaneous mass spectrometry measurements were used to better understand the formation of the DTA response. Comparable DSC investigations were then conducted. Finally, the behavior of catalyst was compared with two commercial palladium/alumina catalysts using DTA and DSC. Our investigations show that DTA and DSC are powerful methods to identify potential catalysts in a fast and reproducible manner, provided that all parameters influencing the thermal signal are kept constant.

A deep learning approach for state-of-health estimation of lithium-ion batteries based on differential thermal voltammetry and attention mechanism

Accurate estimation of the State of Health (SOH) of lithium-ion batteries is crucial for ensuring their safe and reliable operation. Data-driven methods have shown excellent performance in estimating SOH, but obtaining high-quality and strongly correlated features remains a major challenge for these methods. Moreover, different features have varying importance in both spatial and temporal scales, and single data-driven models are unable to capture this information, leading to issues with attention dispersion. In this paper, we propose a data-driven method for SOH estimation leveraging the Bi-directional Long Short-Term Memory (Bi-LSTM) that uses the Differential Thermal Voltammetry (DTV) analysis to extract features, and incorporates attention mechanisms (AM) at both temporal and spatial scales to enable the model focusing on important information in the features. The proposed method is validated using the Oxford Battery degradation Dataset, and the results show that it achieves high accuracy and robustness in SOH estimation. The Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE) are around 0.4% and 0.3%, respectively, indicating the potential for online application of the proposed method in the cyber hierarchy and interactional network (CHAIN) framework.

Synthesis and Characterization of Cellulose Based Injectable Polyurethane Gels

This article describes the synthesis and characterization of cellulose-based injectable polyurethane gels for tissue engineering applications. The gels were prepared by combining a cellulose derivative with a polyurethane precursor and crosslinking agent to form a stable gel under physiological conditions. The resulting gels were evaluated for swelling behavior.
 The addition of cellulose to polyurethane is a promising approach to improve the properties of polyurethane. Cellulose is an abundant, environmentally friendly and inexpensive polysaccharide polymer widely used in hydrogels, pharmaceuticals and agriculture. The obtained cellulose-based polyurethane composites were characterized in detail using various techniques such as Fourier transform infrared spectroscopy (FTIR), Thermogravimetric Analyzer (TGA), Differential Scanning Calorimeter (DSC), Differential Thermal Analysis (DTA), swelling test measurements and optical microscopy. The results showed that the obtained composites are suitable for the production of injectable insulating materials. The paper also briefly discusses the various uses of polyurethanes in different fields, including furniture manufacturing, medical devices such as hospital beds, catheters, injection-coated devices, wound dressings and surgical dressings, as well as marine, air and land vehicles. In conclusion, this paper provides valuable insights into the development of cellulose-based injectable polyurethane gels for tissue engineering applications and highlights the potential of cellulose as an additive to enhance the properties of polyurethane. The results of this study may contribute to the development of new and improved biomaterials for tissue engineering applications.

THE CATALYTIC EFFECT OF ZINC-OXIDE (ZNO) ON THE KINETICS OF COMBUSTION REACTIONS OF SOLID WASTE MATERIALS

This study aims to determine the catalytic effect of ZnO on the kinetics of the decomposition reaction of burning solid waste. ZnO catalyst was chosen because it has high mobility and reactivity. samples were prepared and randomly selected consisting of 12 types of inorganic waste and 10 types of organic waste. The research instrument uses (DTA) Differential Thermal Analysis proximate testing. From this test the data in the form of a mass decrease graph will be analyzed descriptively. The description of the data is displayed through the TG-DTG curve and the calculation of the activation energy (Ea) using the fitting model. the DTG curve identifies three peaks indicating the decomposition stages of the three components have different characteristics. The decomposed components are 1. lignocellulosic organic and low stability organic components, 2. Volatile substances from plastic components, 3. hydrocarbon residues and ash reformation. The combustion temperature increases in samples with high catalyst concentrations, but the burnout temperature decreases in samples with high catalyst concentrations. The DTA curve shows the increased reactivity of samples with high catalyst concentrations. Oxidative reactions which are exothermic/external heating increase in samples with high catalyst concentrations. The catalytic effect on the addition of zinc-oxide (ZnO) catalyst concentration to the components showed a decrease in the hydrocarbon component and an increase in the short chain hydrocarbon component. Increasing the concentration of zinc-oxide (ZnO) catalyst in the sample increases the activation energy. However, overall the addition of catalyst concentration in the combustion of organic-inorganic solid waste samples was able to reduce the activation energy at the end of the combustion reaction

Mechanism and kinetics of thermal processes in Ge0.99Nd0.01S compound

The mechanism and kinetics of thermal processes in the Ge0.99Nd0.01S compound were studied. The thermal parameters were studied by the Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) in the temperature range 25 0C ≤ T ≤ 800 0C. Several thermal transitions were observed in the specified temperature range and the nature of these transitions is explained. It was determined that in the temperature range of 494 0C ≤ T ≤ 601 0C, a thermoeffect observed with energy absorption in the Ge0.99Nd0.01S compound. Mass loss of 38.84% was observed during this effect with phase transition from solid to liquid.

Manifestation of Differential Thermal Expansion in Teflon Guide Bushes/Pads

Manifestation of Differential Thermal Expansion in Teflon Guide Bushes/Pads

Ugi‐modified nano NaY zeolite for the synthesis of new 1,5‐dihydro‐2H‐pyrrol‐2‐ones under mild conditions

In this study, it was aimed to modify the nano zeolite surface via a multi‐component reaction to obtain high functionality in one pot process. For this purpose, the Ugi‐reaction was applied for the first time to develop a novel hydrogen‐bonding nanocatalyst. The nano NaY zeolite was post‐modified using 3‐aminopropyltriethoxysilane (APTES), followed by the Ugi reaction with salicylaldehyde, tert‐butyl isocyanide, and acetic acid to create carboxamide‐functionalized nano NaY. The presence of hydroxyl groups, pores, and carboxamide moieties on the surface of nano zeolite could improve the reactivity, dispersibility, and hydrogen bonding formation capability of the nano zeolite. The formation of the nanocatalyst was investigated by Dynamic Light Scattering (DLS), X‐Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Fourier Transform Infrared spectroscopy (FT‐IR), Thermogravimetric Analysis (TGA), Transmission Electron Microscopy (TEM), Brunauer–Emmett–Teller (BET), Scanning Electron Micrograph (SEM), Elemental analyses, and Energy Dispersive Spectroscopy (EDS). The catalytic activity of the synthesized modified nano zeolite was examined in the three component‐reaction of aldehydes, amines, and ethyl pyruvate to obtain new pyrrol derivatives in high yields under mild conditions. After separation by filtration, the catalyst can be recycled for up to seven subsequent runs without any appreciable activity loss. Thus, the titled heterocycles can be prepared in an eco‐friendly manner since the catalyst is easily recovered and reused, and the procedure is simple to perform. The results indicated that the catalytic system developed in this study may be useful for the preparation of other beneficial heterocyclic compounds under environmentally benign conditions.

Growth and characterization of Oxalic acid doped Guanidine carbonate (OGC) single crystal

Oxalic acid doped Guanidine carbonate, an organic nonlinear optical single crystal is developed successfully by slow evaporation solution growth method using deionized water as a solvent. The crystal structure and lattice parameters of grown crystals are determined by single crystal X – ray diffraction of the grown crystal. The presence of expected functional groups of the grown crystal is identified by Fourier Transform Infrared spectroscopy. The optical transmittance spectrum of the crystals has been recorded by UV –Vis-NIR spectral analysis. The calculated large bandgap of the grown crystals attests them for optoelectronic applications. The Thermo Gravimetric and Differential Thermal analyses have been carried out to understand the thermal responses of the crystals. Second harmonic generation efficiency of the grown crystals have been calculated by Kurtz powder method. Nd – YAG laser (1064 nm) was used to find out the laser damage threshold of the grown crystal. The inspiring results confirms that the grown crystal serve as a potential candidate for photonic devices.

The influence of the ageing temperature on different properties of the EN AW-7075 aluminium alloy

The influence of the ageing temperature on the hardness, electrical conductivity, thermal diffusivity and thermal conductivity of the EN AW-7075 aluminium alloy was studied in this paper. After solution treating the alloy at 480 °C for 1 h and quenching it in ice water, the investigated alloy was characterized using Differential Thermal Analysis (DTA) in order to determine the optimal temperatures for the isochronal ageing treatments. Afterwards, isochronal ageing was conducted at the temperature range of 110 °C-250 °C for 30 min The hardness, electrical conductivity, thermal diffusivity, thermal conductivity and microstructural features were investigated during the ageing treatments. Hardness had a peak value after ageing at 150 °C, while other properties gradually increased with the ageing temperature. Microstructural investigation of the aged alloy by SEM-EDS revealed the existence of precipitated phases that appear homogenously distributed in the microstructure.

Crystallization kinetics analysis of Ge18BixSe82-x chalcogenide glasses alloys by using non-isothermal methods

The melt quench method is used to prepare the chalcogenide glass Ge18BixSe82-x (x: 0.5, 2, 4, 6, and 8 at percent). The samples are characterized using X-ray diffraction (XRD) and a scan electron microscope (SEM). The kinetics of crystallization of the chalcogenide glasses under consideration are investigated by using Differential Thermal Analysis (DTA) under non-isothermal conditions. Different models are used to calculate the activation energy of crystallization (Ec). The Kissenger-Akahira-Sunose (KAS) method is used to calculate the change of activation energy with crystallization volume fraction (Ecα). As well, the activation energy of glass transitions is measured by using different models. The results of fitting the experimental DTA data to the computed DTA curves show that the Johnson-Mehl-Avrami (JMA) model cannot represent the crystallization process of Ge18BixSe82-x glass. Our findings show that the Sestak-Berggren (SB) model is better suited to describe the crystallization process for the glass under investigation.

Effect of chemical treatment on the physical and thermal stabillity of Hibiscus Tiliaceus Bark Fiber (HBF) as reinforcement in composite

Natural fibers, as reinforcing agents in polymer composites, have great potential for development due to their various advantages, such as toughness, strength, and low density. However, low thermal stability is a significant issue in multiple applications of composite materials. This study aims to explores the potential of using natural fibers as reinforcing agents in polymer composites by investigating the effect of different chemical treatments of sodium hydroxide, (3-Aminopropyl)trimethoxysilane, and a combination of both on the thermal stability of Hibiscus Tiliaceus Bark Fiber (HBF). The thermal stability of HBF was evaluated using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), X-Ray Fluorescence (XRF), Differential Thermal Analysis (DTA), and Thermogravimetric Analysis (TGA). The investigation results showed that the physical properties and thermal stability were affected by chemical treatments of NaOH Silane. The cellulose decomposition occurred at a temperature range of 340–360 °C, leading to a 68.9528% reduction in the sample weight. These findings were validated by SEM observations and XRF tests, which demonstrated improved fiber surface cleanliness, a 1.01% increase in the O/C ratio, and a 16% increase in silicon minerals.

Development of Halloysite Loaded Polypropylene Sutures with Enhanced Mechanical and Thermal Properties

Polypropylene is a crucial polymeric material in modern life, especially in the packaging and food industry, as well as the biomedical field. This study aimed to enhance the mechanical properties of polypropylene structures used as surgical suture material by preparing polypropylene-halloysite (PP-halloysite) composites. Halloysite was added in varying amounts (1%, 3%, 5%, and 10%) to polypropylene, and the resulting composites were passed through a double heated extruder. Structural characterization of the PP-halloysite composites was carried out using Fourier Transform Infrared Spectroscopy (FTIR), elemental analysis, Scanning Electron Microscopy-Energy Dispersive X-Ray Analysis (SEM-EDX), Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA) ), and Differential Scanning Calorimetry (DSC) techniques to determine their thermal properties and softening temperatures. Mechanical tests were conducted to examine the composite suture structures obtained and determine the effect of halloysite doping on their mechanical properties. The results of the mechanical tests showed that the mechanical strength of the fiber structure increased with the amount of halloysite added. Therefore, the PP-halloysite suture structures could be used as non-melting suture material, especially in surgeries that require high strength compared to pure polypropylene structures.

The dissolution of p-methoxycinnamic acid-β-cyclodextrin inclusion complex produced with microwave irradiation.

p-methoxycinnamic acid (pMCA) is an ethyl pmethoxycinnamic derivative, which is the largest active ingredient in the rhizome of the kencur (Kaempferia galanga L) plant. Several studies reported that the compound has anti-inflammatory activity but has low solubility in water. The formation of a pMCA-β- cyclodextrin (βCD) inclusion complex with a molar ratio of 1:1 can increase its solubility. The formation of inclusion complexes with conventional methods requires a long time and the yield value is not optimal. This study aims to evaluate the dissolution of the pMCA-βCD inclusion complex produced using the microwave irradiation method. The product was manufactured with chloroform solvent and a power of 400 watts (power 80%). It was then evaluated using the Differential Thermal Analysis (DTA) every 2 minutes until the 8th minute. The reaction was complete after 4 minutes of treatment with a yield of 96.5%. The obtained inclusion complexes were evaluated using DTA, FTIR, and PXRD. Subsequently, a dissolution test was carried out using a type 2 apparatus in distilled water medium of pH 6.8±0.05 at 37±0.5°C. The results showed that there was a change in the melting temperature profile, infrared spectra, and crystallinity of the product. An 89.18% dissolution was also obtained within 60 minutes, which was twice that of pMCA compounds. From the results of the study, it can be concluded that the formation of pMCA-βCD inclusion complexes using the microwave irradiation method is capable of providing high-yield values in a short time.

Development of polypropylene membranes grafted with nanocellulose to analyze organic pollutants in environmental waters using miniaturized passive samplers based on liquid-phase microextraction

Reinforcing hollow polypropylene fibers with nanocellulose is a viable alternative for implementing miniaturized passive sampling devices (MPSDs) based on liquid-phase microextraction (LPME). This modification improves the extractive properties of microporous membranes, including the sensitivity to fluctuations in the uptake steps. The new material, polypropylene hollow fiber grafted with nanocellulose, was developed and characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive System (EDS) and Thermogravimetric (TGA) and Differential Thermal (DTA) analysis. The morphology type of the crystallite of cellulose most abundant after chemical regeneration was the CII (Celulose II) allomorphic. Sorption studies were carried out and revealed that the modified membrane could absorb 177% more water than its untreated commercial counterpart, making it suitable for long-term sampling. Miniaturized passive sampling devices were equipped with the new material, and the devices were deployed in situ for passive sampling of organic pollutants in environmental waters of marginal lagoons. Fingerprint analysis of samples was performed by comprehensive two-dimensional gas chromatography coupled with mass spectrometry and identified a variety of pollutants such as pesticides, plasticizers and prescription and illegal drugs and their metabolites. Therefore, these MPSDs can be employed for the sampling and long-term monitoring of water contaminants with a wide range of polarities.

Impact of Thermal-Hydraulic Feedback and Differential Thermal Expansion on European Sodium-Cooled Fast Reactor Core Power Distribution

AbstractThe objective of this paper is to quantify the coupling effect on the power distribution of sodium-cooled fast reactors (SFRs), specifically the European SFR. Calculations are performed with several state-of-the-art reactor physics and Multiphysics codes (TRACE/PARCS, DYN3D, WIMS, COUNTHER, and GeN-Foam) to build confidence in the methodologies and validity of results. Standalone neutronic calculations were generally in excellent agreement with a reference Monte Carlo-calculated power distribution (from Serpent). Next, the impact of coolant density and fuel temperature Doppler feedback was calculated. Reactivity coefficients for perturbations in the inlet temperature, coolant heat up and core power was shown to be negative with values of around −0.5 pcm/°C, −0.3 pcm/°C, and −3.5 pcm/%, respectively. Fuel temperature and coolant density feedback was found to introduce a roughly −1%/+1% in/out power tilt across the core. Calculations were then extended to axial expansion for cases where fuel is linked and unlinked to the clad. Core calculations are in good agreement with each other. The impact of differential fuel expansion is found to be larger for fuel both linked and unlinked to the clad, with the in/out power tilt increasing to around −4%/+2%. Thus, while broadly confirming the known result that standalone physics calculations give good results, the expansion coupling effect is perhaps more than anticipated a priori. These results provide a useful benchmark for the further development of Multiphysics codes and methodologies in support of advanced reactor calculations.

Preparation and mechanical properties of jute fibre composite by using modified unsaturated polyester resin

The polyester resin has been synthesized using maleic anhydride, phthalic anhydride and propylene glycol. Synthesized resin, styrene and jute fibre along with a catalyst were used for the composite preparation. The mechanical and thermal properties of composites were evaluated. The obtained composites were characterized by TGA (Thermal Gravimetric Analysis) and DTA (Differential Thermal Analysis).

An Active Pixel-Matrix Electrocaloric Device for Targeted and Differential Thermal Management.

More than 55% of electronic failures are caused by damage from localized overheating. Up to now, there is still no efficient method for targeted temperature control against localized overheating. Although some existing thermal management devices handle this issue by full coverage cooling, it generates a lot of useless energy consumption. Here, a highly efficient pixel-matrix electrocaloric (EC) cooling device is reported, which can realize a targeted and differential thermal management. The modified poly(vinylidene fluoride-tertrifluoroethylene-chlorofluoroethylene) reaches a large adiabatic temperature change of 7.8 K and is more suitable for thermal transfer and electrostatic actuation at high frequencies. All active pixels in the EC cooling device exhibit a stable temperature span of 4.6 K and a heat flux of 62mWcm-2 , which is more than twice that of the one-layer EC device. Each refrigeration pixel can be independently controlled and effectively cooled down the localized overheating site(s) in situ. The surface temperature of the simulated central processing unit decreases by 33.2 K at 120 s after applying this EC device. Such a compact, embeddable, low cost, and active solid-state pixel-matrix cooling device has great potential for localized overheating protection in microelectronics.

Preparation and analysis of pure and surface modified nanohydroxyapatite derived from eggshells and its in-vitro studies for bone graft applications

The need and significance for quality bone graft substitute increases due to the worldwide increment in the health problems such as osteoporosis, accidental loss and teeth decay etc. Nowadays, nanohydroxyapatite and its polymeric composites are effectively used as bone grafts and dentin. In this work, nanohydroxyapatite (nHAp) and surface-modified nanohydroxyapatite were synthesized through the precipitation method using bio-wastes (eggshells) as a Calcium precursor. The polymers Polyethylene glycol (PEG) and polyvinyl acrylate (PVA) were used as surface modifiers to control the particle size. The prepared samples were analyzed through X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Differential Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HR-TEM) and X-ray Photoelectronic Spectroscopy (XPS). Also, the samples were subjected to simulated body fluid analysis, antimicrobial and hemolytic assay to analyze the apatite forming ability and hemolytic nature. The XRD, SEM and HR-TEM results show the crystallite and particle sizes are about 41 nm, 57 nm and 66.6 nm (rod-shaped) respectively. While the EDAX spectra show the presence of Calcium, Phosphate, Oxygen and Sodium in the prepared sample. However, the FT-IR spectra confirm the presence of OH, PO43−, and CO32− functional groups in the sample. The thermogram depicts the stability of nHAp/PVA composite is better than nHAp without polymer. This study reports that reprocessing of eggshells to nHAp and its composites paves the way to recover the ecosphere and the obtained value-added product, which may use in making a promising material for bone implants, dental fillers and coatings at low cost.

Lithium-ion Differential Thermal Analysis Studies of the Effects of Long-Term Li-ion Cell Storage on Electrolyte Composition and Implications for Cell State of Health

Li-ion cells being developed for long lifetime applications are often subjected to storage tests at various states-of-charge and various temperatures. Storage is interrupted from time to time for reference performance tests so that cell capacity and impedance can be checked. These reference performance tests give no information about any compositional changes that may have occurred in the electrolyte. Lithium-ion differential thermal analysis applied to cells after years of storage can be used to determine if the electrolyte has changed significantly due to unwanted reactions with the electrode materials or if little to no change has occurred. Here, Li-ion differential thermal analysis is used to study electrolyte changes in a more-or-less “yes/no” manner for single crystal NMC532/graphite cells stored between 3.67 and 4.3 V at 20, 40 and 55 °C for up to five years. Such measurements can be used to give confidence about lifetime predictions. Several such cells are detailed here, with correlation between degree of cell degradation and degree of change in electrolyte composition. Relationships are shown between degradation and evolution of state of electrolyte in elevated temperature and voltage storage experiments.

Monitoring Changes in Electrolyte Composition of Commercial Li-Ion Cells after Cycling using NMR Spectroscopy and Differential Thermal Analysis

We illustrate a simple and effective electrolyte extraction methodology from commercial 18650 lithium-ion cells. This methodology is based on a liquid-liquid extraction step, which is highlighted for robustness, reproducibility, and reliability. We assess the consumption of electrolyte by tracking compositional changes using liquid-state nuclear magnetic resonance (NMR) spectroscopy, supported by differential thermal analysis (DTA) before and after cell cycling. An analysis method that monitors compositional dynamics is presented and shows the impact of these changes throughout a cell’s lifetime. Such methodology can be employed in the understanding of electrolyte degradation mechanisms to enhance the understanding of performance fade in commercial cells. Moreover, it will help build robust mathematical models that are able to predict the drive of cell degradation and ultimate failure.